An existing unidirectional ratchet wrench is formed by wedging a plurality of C-shaped steel sheets between an annular head and a ratchet. The number of the C-shaped steel sheets effects the operation of the ratchet. Further, the structures of the C-shaped steel sheets may be damaged due to the excessive large action force. In addition, a steel block could not have the same elastic effect as the steel sheets if the block steel is processed by a conventional treatment technique of the steel sheet. Furthermore, the cutting of the steel sheet is another difficult problem. Moreover, the use of the plurality of steel sheets increases the cost and is easier to cause problems and inconvenience in an assembly process. Due to the limitation of the exist techniques of treating the steel, the aforementioned problems caused by using the plurality of steel sheets cannot be solved.